CN116922612A - Cooling and discharging process of high-fluidity nylon - Google Patents
Cooling and discharging process of high-fluidity nylon Download PDFInfo
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- CN116922612A CN116922612A CN202210371369.8A CN202210371369A CN116922612A CN 116922612 A CN116922612 A CN 116922612A CN 202210371369 A CN202210371369 A CN 202210371369A CN 116922612 A CN116922612 A CN 116922612A
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- 229920001778 nylon Polymers 0.000 title claims abstract description 98
- 239000004677 Nylon Substances 0.000 title claims abstract description 82
- 238000001816 cooling Methods 0.000 title claims abstract description 31
- 238000000034 method Methods 0.000 title claims abstract description 28
- 238000007599 discharging Methods 0.000 title claims abstract description 25
- 238000006116 polymerization reaction Methods 0.000 claims abstract description 31
- 238000003756 stirring Methods 0.000 claims abstract description 17
- 238000002425 crystallisation Methods 0.000 claims abstract description 14
- 230000008025 crystallization Effects 0.000 claims abstract description 14
- 239000012299 nitrogen atmosphere Substances 0.000 claims abstract description 13
- 238000001035 drying Methods 0.000 claims abstract description 12
- 238000009740 moulding (composite fabrication) Methods 0.000 claims abstract description 4
- JBKVHLHDHHXQEQ-UHFFFAOYSA-N epsilon-caprolactam Chemical compound O=C1CCCCCN1 JBKVHLHDHHXQEQ-UHFFFAOYSA-N 0.000 claims description 22
- 238000006243 chemical reaction Methods 0.000 claims description 18
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 238000007151 ring opening polymerisation reaction Methods 0.000 claims description 14
- 239000000178 monomer Substances 0.000 claims description 13
- 238000000465 moulding Methods 0.000 claims description 13
- SLXKOJJOQWFEFD-UHFFFAOYSA-N 6-aminohexanoic acid Chemical compound NCCCCCC(O)=O SLXKOJJOQWFEFD-UHFFFAOYSA-N 0.000 claims description 11
- 229960002684 aminocaproic acid Drugs 0.000 claims description 11
- 239000006085 branching agent Substances 0.000 claims description 11
- KDXKERNSBIXSRK-UHFFFAOYSA-N Lysine Natural products NCCCCC(N)C(O)=O KDXKERNSBIXSRK-UHFFFAOYSA-N 0.000 claims description 8
- 239000004472 Lysine Substances 0.000 claims description 8
- 239000003505 polymerization initiator Substances 0.000 claims description 7
- DVPHDWQFZRBFND-DMHDVGBCSA-N 1-o-[2-[(3ar,5r,6s,6ar)-2,2-dimethyl-6-prop-2-enoyloxy-3a,5,6,6a-tetrahydrofuro[2,3-d][1,3]dioxol-5-yl]-2-[4-[(2s,3r)-1-butan-2-ylsulfanyl-2-(2-chlorophenyl)-4-oxoazetidin-3-yl]oxy-4-oxobutanoyl]oxyethyl] 4-o-[(2s,3r)-1-butan-2-ylsulfanyl-2-(2-chloropheny Chemical group C1([C@H]2[C@H](C(N2SC(C)CC)=O)OC(=O)CCC(=O)OC(COC(=O)CCC(=O)O[C@@H]2[C@@H](N(C2=O)SC(C)CC)C=2C(=CC=CC=2)Cl)[C@@H]2[C@@H]([C@H]3OC(C)(C)O[C@H]3O2)OC(=O)C=C)=CC=CC=C1Cl DVPHDWQFZRBFND-DMHDVGBCSA-N 0.000 claims description 6
- KWYUFKZDYYNOTN-UHFFFAOYSA-M Potassium hydroxide Chemical compound [OH-].[K+] KWYUFKZDYYNOTN-UHFFFAOYSA-M 0.000 claims description 6
- HEMHJVSKTPXQMS-UHFFFAOYSA-M Sodium hydroxide Chemical compound [OH-].[Na+] HEMHJVSKTPXQMS-UHFFFAOYSA-M 0.000 claims description 6
- 125000000524 functional group Chemical group 0.000 claims description 6
- 238000005453 pelletization Methods 0.000 claims description 5
- 150000001413 amino acids Chemical class 0.000 claims description 4
- YTVNOVQHSGMMOV-UHFFFAOYSA-N naphthalenetetracarboxylic dianhydride Chemical compound C1=CC(C(=O)OC2=O)=C3C2=CC=C2C(=O)OC(=O)C1=C32 YTVNOVQHSGMMOV-UHFFFAOYSA-N 0.000 claims description 4
- 230000035484 reaction time Effects 0.000 claims description 4
- FAGUFWYHJQFNRV-UHFFFAOYSA-N tetraethylenepentamine Chemical compound NCCNCCNCCNCCN FAGUFWYHJQFNRV-UHFFFAOYSA-N 0.000 claims description 3
- VILCJCGEZXAXTO-UHFFFAOYSA-N 2,2,2-tetramine Chemical compound NCCNCCNCCN VILCJCGEZXAXTO-UHFFFAOYSA-N 0.000 claims description 2
- RPNUMPOLZDHAAY-UHFFFAOYSA-N Diethylenetriamine Chemical compound NCCNCCN RPNUMPOLZDHAAY-UHFFFAOYSA-N 0.000 claims description 2
- KDXKERNSBIXSRK-YFKPBYRVSA-N L-lysine Chemical compound NCCCC[C@H](N)C(O)=O KDXKERNSBIXSRK-YFKPBYRVSA-N 0.000 claims description 2
- JHWNWJKBPDFINM-UHFFFAOYSA-N Laurolactam Chemical compound O=C1CCCCCCCCCCCN1 JHWNWJKBPDFINM-UHFFFAOYSA-N 0.000 claims description 2
- 150000008065 acid anhydrides Chemical class 0.000 claims description 2
- 229910052783 alkali metal Inorganic materials 0.000 claims description 2
- 150000001340 alkali metals Chemical class 0.000 claims description 2
- 150000001412 amines Chemical class 0.000 claims description 2
- 125000003277 amino group Chemical group 0.000 claims description 2
- 150000008064 anhydrides Chemical class 0.000 claims description 2
- CJYXCQLOZNIMFP-UHFFFAOYSA-N azocan-2-one Chemical compound O=C1CCCCCCN1 CJYXCQLOZNIMFP-UHFFFAOYSA-N 0.000 claims description 2
- 125000003178 carboxy group Chemical group [H]OC(*)=O 0.000 claims description 2
- 125000002887 hydroxy group Chemical group [H]O* 0.000 claims description 2
- 229920000768 polyamine Polymers 0.000 claims description 2
- 150000007519 polyprotic acids Polymers 0.000 claims description 2
- HNJBEVLQSNELDL-UHFFFAOYSA-N pyrrolidin-2-one Chemical compound O=C1CCCN1 HNJBEVLQSNELDL-UHFFFAOYSA-N 0.000 claims description 2
- LFQSCWFLJHTTHZ-UHFFFAOYSA-N Ethanol Chemical compound CCO LFQSCWFLJHTTHZ-UHFFFAOYSA-N 0.000 claims 1
- 238000002360 preparation method Methods 0.000 abstract description 7
- 239000000463 material Substances 0.000 abstract description 6
- 238000010438 heat treatment Methods 0.000 description 15
- IJGRMHOSHXDMSA-UHFFFAOYSA-N nitrogen Substances N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 9
- 229910052757 nitrogen Inorganic materials 0.000 description 7
- 239000000376 reactant Substances 0.000 description 7
- 230000000052 comparative effect Effects 0.000 description 5
- 239000000203 mixture Substances 0.000 description 5
- QJGQUHMNIGDVPM-UHFFFAOYSA-N nitrogen group Chemical group [N] QJGQUHMNIGDVPM-UHFFFAOYSA-N 0.000 description 5
- 238000006467 substitution reaction Methods 0.000 description 5
- 239000004952 Polyamide Substances 0.000 description 4
- 229920002647 polyamide Polymers 0.000 description 4
- 239000000243 solution Substances 0.000 description 4
- 238000000048 melt cooling Methods 0.000 description 3
- 238000002844 melting Methods 0.000 description 3
- 230000008018 melting Effects 0.000 description 3
- QAOWNCQODCNURD-UHFFFAOYSA-N sulfuric acid Substances OS(O)(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-N 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 238000011049 filling Methods 0.000 description 2
- 239000007788 liquid Substances 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 239000002245 particle Substances 0.000 description 2
- 229920000642 polymer Polymers 0.000 description 2
- 238000012545 processing Methods 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- 238000010146 3D printing Methods 0.000 description 1
- 238000012935 Averaging Methods 0.000 description 1
- 229920002302 Nylon 6,6 Polymers 0.000 description 1
- 238000005299 abrasion Methods 0.000 description 1
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- 125000003368 amide group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 238000012512 characterization method Methods 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 238000000605 extraction Methods 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000001746 injection moulding Methods 0.000 description 1
- 229910052500 inorganic mineral Inorganic materials 0.000 description 1
- 150000003951 lactams Chemical class 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 239000007769 metal material Substances 0.000 description 1
- 239000011707 mineral Substances 0.000 description 1
- 238000002156 mixing Methods 0.000 description 1
- 239000008188 pellet Substances 0.000 description 1
- 239000002861 polymer material Substances 0.000 description 1
- 239000011208 reinforced composite material Substances 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 150000005846 sugar alcohols Polymers 0.000 description 1
- 238000005303 weighing Methods 0.000 description 1
Classifications
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B9/00—Making granules
- B29B9/02—Making granules by dividing preformed material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B29—WORKING OF PLASTICS; WORKING OF SUBSTANCES IN A PLASTIC STATE IN GENERAL
- B29B—PREPARATION OR PRETREATMENT OF THE MATERIAL TO BE SHAPED; MAKING GRANULES OR PREFORMS; RECOVERY OF PLASTICS OR OTHER CONSTITUENTS OF WASTE MATERIAL CONTAINING PLASTICS
- B29B13/00—Conditioning or physical treatment of the material to be shaped
- B29B13/06—Conditioning or physical treatment of the material to be shaped by drying
Landscapes
- Engineering & Computer Science (AREA)
- Mechanical Engineering (AREA)
- Polyamides (AREA)
Abstract
The invention belongs to the technical field of nylon material preparation, and discloses a cooling and discharging process of high-fluidity nylon, which comprises the following steps: cooling the nylon melt prepared by the polymerization reaction, then discharging, forming, drying and granulating to obtain a high-fluidity nylon slice; the cooling conditions include: in the nitrogen atmosphere and stirring state, the temperature is reduced to 185-220 ℃ at a constant speed of 0.25-8.0 ℃/min within 10-40 minutes. The invention solves the problem that the high-fluidity nylon cannot be molded due to the too low viscosity and difficult crystallization in the discharging and granulating process, can realize the preparation of the high-fluidity nylon on the existing common nylon preparation device, and can produce nylon products with high flexibility, rich types and wide application prospect.
Description
Technical Field
The invention belongs to the technical field of nylon material preparation, and particularly relates to a cooling and discharging process of high-fluidity nylon.
Background
Polyamide (PA) is commonly called nylon (nylon), which is a polymer with amide groups (-CONH-) on the main chain, and nylon materials have gained a significant position in high polymer materials since 80 years of development since the beginning of the production of nylon 66 by dupont in 1939. The nylon has good comprehensive properties including mechanical property, heat resistance, abrasion resistance, chemical resistance and self-lubricating property, low friction coefficient, certain flame retardance and easy processing, and is suitable for material filling enhancement modification. The number of the commercial polyamide varieties is more than 20, and the polyamide has wide application in the fields of clothing, daily necessities, automobiles, electronic and electrical, 3D printing and the like.
With the increasing demand of automobile light weight, more and more metal materials are replaced by nylon materials, and higher demands are also put on the material performance. The high-fluidity nylon has the characteristics of easy molding, excellent product surface performance and the like, has low processing temperature and injection molding pressure and short molding cycle, and has obvious advantages in the aspect of preparing high-mineral filling and high-content glass fiber reinforced composite materials. According to the molecular branching concept, by introducing a branched chain structure into a high molecular structure, the high polymer is converted from a linear structure into a three-dimensional spherical structure, and higher fluidity can be obtained under the condition that the molecular weight is not obviously reduced.
The common nylon preparation process directly discharges nylon melt after polymerization, crystallization molding is carried out, then the nylon melt is granulated by a granulator, and then the nylon slice finished product is obtained after extraction and drying. The high-fluidity nylon has too low viscosity, and the crystallization is difficult in the process of discharging and granulating after polymerization, so that the nylon cannot be molded, and the subsequent processes such as granulating, extracting, drying and the like cannot be performed.
Disclosure of Invention
Aiming at the situation, the invention aims to provide a cooling and discharging process of high-fluidity nylon. The process can solve the problems that the high-fluidity nylon produced by the prior art cannot be molded and cut into particles due to too low viscosity and difficult crystallization in the discharging process after polymerization.
The invention provides a cooling and discharging process of high-fluidity nylon, which comprises the following steps: cooling the nylon melt prepared by the polymerization reaction, then discharging, forming, drying and granulating to obtain a high-fluidity nylon slice;
the cooling conditions include: in the nitrogen atmosphere and stirring state, the temperature is reduced to 185-220 ℃ at a constant speed of 0.25-8.0 ℃/min within 10-40 minutes.
Compared with the prior art, the invention has the following beneficial effects: according to the invention, through adding the melt cooling step after the polymerization is completed, the problem that the high-fluidity nylon is difficult to crystallize, mold and cut into particles in the discharging process is solved, the preparation of the high-fluidity nylon can be realized on the existing common nylon preparation device, and the produced nylon product has high flexibility, rich types and wide application prospect.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Detailed Description
The following describes specific embodiments of the present invention in detail. It should be understood that the detailed description and specific examples, while indicating and illustrating the invention, are not intended to limit the invention.
The invention provides a cooling and discharging process of high-fluidity nylon, which comprises the following steps: cooling the nylon melt prepared by the polymerization reaction, then discharging, forming, drying and granulating to obtain a high-fluidity nylon slice;
the cooling conditions include: in the nitrogen atmosphere and stirring state, the temperature is reduced to 185-220 ℃ at a constant speed of 0.25-8.0 ℃/min within 10-40 minutes.
Preferably, the cooling conditions include: in the nitrogen atmosphere and stirring state, the temperature is reduced to 190-210 ℃ at a constant speed of 0.75-5.0 ℃/min within 14-40 minutes.
In the present invention, the polymerization reaction may include: in the presence of a ring-opening polymerization initiator, a lactam monomer and a branching agent are subjected to ring-opening polymerization reaction to prepare a nylon melt.
According to the present invention, the ring-opening polymerization initiator may be selected from at least one of water, aminocaproic acid, sodium hydroxide, potassium hydroxide and alkali metal, preferably water, aminocaproic acid.
In the present invention, the lactam monomer may be at least one selected from the group consisting of butyrolactam, caprolactam, heptanolactam, octalactam and dodecalactam, and is preferably caprolactam.
According to the present invention, the branching agent may be selected from at least one of a polybasic acid, a polybasic amine, a polyhydric alcohol, an amino acid or an acid anhydride having 3 or more functional groups, the functional groups being amino groups, carboxyl groups or hydroxyl groups;
preferably, the branching agent is selected from at least one of polyamines, amino acids or anhydrides containing 3 to 6 functional groups;
more preferably, the branching agent is selected from at least one of lysine, naphthalene-1, 4,5, 8-tetracarboxylic dianhydride, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.
In the present invention, the mass ratio of the lactam monomer, the ring-opening polymerization initiator and the branching agent may be 100:2.0 to 20.0:0.05 to 10.0, preferably 100:10.0 to 18.0:0.1 to 5.0.
According to the present invention, the conditions for the ring-opening polymerization reaction include: the reaction temperature is 200-280 ℃, the reaction pressure is 0-0.3MPa, and the reaction time is 1-15 hours;
preferably, the conditions of the ring-opening polymerization reaction include: the reaction temperature is 230-265 ℃, the reaction pressure is 0.05-0.1MPa, and the reaction time is 1.5-10 hours.
In the invention, the discharging molding comprises the following steps: and decompressing the cooled nylon melt to remove unreacted monomers, and then discharging the unreacted monomers into desalted water for crystallization and molding.
According to the invention, the drying and granulating comprises: and drying and granulating the formed nylon to obtain the high-fluidity nylon slice.
The cooling and discharging process of the high-fluidity nylon specifically comprises the following steps:
1) Polymerization reaction: under the condition of ring-opening polymerization reaction, the existence of a ring-opening polymerization initiator enables lactam monomers and branching agents to jointly react until the polymerization is completed;
2) And (5) cooling the melt: under the nitrogen atmosphere, the temperature of the Ni Long Rongti obtained in the step 1) is reduced to 185-220 ℃ at a constant speed of 0.25-8.0 ℃ per minute within 10-40 minutes, and the stirring state is maintained;
3) And (5) discharging and forming: decompressing the nylon melt obtained in the step 2) to remove unreacted monomers, discharging the unreacted monomers from the reaction kettle, and crystallizing and forming the nylon melt in desalted water;
4) Drying and granulating: and (3) drying and granulating the nylon obtained in the step (3) to obtain the high-fluidity nylon slices.
In the invention, the polymerization reaction and the nylon melt cooling are carried out in a reaction kettle, the temperature is reduced after the polymerization reaction is finished, and the temperature before the nylon melt cooling is the temperature of the polymerization reaction.
The substances and process parameters not defined in the invention can be selected according to the prior art, and belong to the conventional technical means in the field.
The invention will be further illustrated with reference to the following examples. But are not limited by these examples.
In the following examples and comparative examples, the data were obtained as follows:
1. relative viscosity test of nylon: and weighing 0.25g of nylon sample into a 25mL volumetric flask, adding concentrated sulfuric acid (below the scale mark), adding the liquid level in the volumetric flask to the scale mark by using the concentrated sulfuric acid after the nylon sample is completely dissolved, and shaking uniformly to perform a test. And measuring 10mL of the prepared solution by using a pipette, adding the solution into a Ubbelohde viscometer with the capillary diameter of 1.0-1.1mm, vertically installing the viscometer in a constant-temperature water bath with the temperature of (25+/-0.5) ℃ for 20 minutes at constant temperature, and measuring the time between two scale marks of the solution flowing through the viscometer, namely the flowing time t of the solution. The flow-through time of the pure solvent concentrated sulfuric acid is t 0 . Each sample was tested 3 times and the error was no more than + -0.2 s before and after averaging. The relative viscosity η of a nylon sample can be calculated according to the following formula:
2. melting point and crystallization temperature of nylon were tested: a TA company Q100 series thermal analyzer was used. The nylon cast film sample was placed in an aluminum crucible at an experimental temperature ranging from 0-260 ℃. Firstly, heating to 260 ℃ at a heating rate of 10 ℃/min, preserving heat for 5min, then cooling, wherein the cooling rate is 10 ℃/min, and then performing a second heating scan at a heating rate of 10 ℃/min.
Example 1
140.47 g of caprolactam, 21.12 g of aminocaproic acid and 1.42 g of lysine are added into a polymerization reaction kettle, after nitrogen substitution, stirring and heating are carried out to 175 ℃ to enable reactants to be in a uniformly mixed molten state, normal pressure is maintained, the temperature is raised to 258 ℃, heating is turned off after polymerization is carried out for 2 hours, cooling to 210 ℃ is carried out at a constant speed of 1.6 ℃/min in a nitrogen atmosphere, the stirring state is maintained, then unreacted monomers are removed under 2000Pa pressure, the nylon melt is discharged to desalted water, crystallization molding and pelletization are carried out, and the high-fluidity nylon polymer slice P1 is obtained.
The relative viscosity of the high-fluidity nylon polymer P1 was measured to be 2.01.
Example 2
141.78 g of caprolactam, 19.70 g of aminocaproic acid and 2.81 g of lysine are added into a polymerization reaction kettle, after nitrogen substitution, stirring and heating are carried out to 180 ℃ to enable reactants to be in a uniformly mixed molten state, normal pressure is maintained, the temperature is raised to 260 ℃ and then heating is turned off after polymerization is carried out for 3 hours, the temperature is reduced to 205 ℃ at a constant speed of 2.5 ℃ per minute in 22 minutes under the nitrogen atmosphere, the stirring state is maintained, then unreacted monomers are removed under 2000Pa pressure, the nylon melt is discharged to desalted water, crystallization molding and granulating are carried out, and the high-fluidity nylon polymer slice P2 is obtained.
The relative viscosity of the high-fluidity nylon polymer P2 was measured to be 1.86.
Example 3
140.46 g of caprolactam, 20.46 g of aminocaproic acid and 7.02 g of lysine are added into a polymerization reaction kettle, after nitrogen substitution, stirring and heating are carried out to 170 ℃ to enable reactants to be in a uniformly mixed molten state, normal pressure is maintained, the temperature is raised to 265 ℃, heating is turned off after polymerization is carried out for 4 hours, cooling to 195 ℃ at a constant speed of 2.0 ℃ per minute is carried out in a nitrogen atmosphere, the stirring state is maintained, then unreacted monomers are removed under 2000Pa pressure, the nylon melt is discharged to desalted water, crystallization molding and pelletization are carried out, and high-fluidity nylon polymer chips P3 are obtained.
The relative viscosity of the high-fluidity nylon polymer P3 was measured to be 1.68.
Example 4
140.48 g of caprolactam, 23.63 g of aminocaproic acid and 0.70 g of naphthalene-1, 4,5, 8-tetracarboxylic dianhydride are added into a polymerization reactor, after nitrogen substitution, the mixture is stirred and heated to 195 ℃ to enable reactants to be in a molten state which is uniformly mixed, normal pressure is kept, the temperature is raised to 255 ℃, the heating is turned off after polymerization is carried out for 2 hours, the mixture is cooled to 220 ℃ at a constant speed of 1.0 ℃/min in the nitrogen atmosphere and kept in a stirring state, unreacted monomers are removed under the pressure of 2000Pa, and then nylon melt is discharged to desalted water, crystallized, molded and pelletized to obtain the high-fluidity nylon polymer chips P4.
The relative viscosity of the high-fluidity nylon polymer P4 was measured to be 2.49.
Example 5
140.89 g of caprolactam, 20.29 g of aminocaproic acid and 1.37 g of naphthalene-1, 4,5, 8-tetracarboxylic dianhydride are added into a polymerization reactor, after nitrogen substitution, the mixture is stirred and heated to 190 ℃ to enable reactants to be in a molten state which is uniformly mixed, normal pressure is kept, the temperature is raised to 260 ℃, the heating is turned off after polymerization for 2.5 hours, the mixture is cooled to 212 ℃ at a constant speed of 1.2 ℃/min in a nitrogen atmosphere, the stirring state is kept, unreacted monomers are removed under 2000Pa pressure, and nylon melt is discharged to desalted water, crystallized, molded and pelletized to obtain high-fluidity nylon polymer chips P5.
The relative viscosity of the high-fluidity nylon polymer P5 was measured to be 2.20.
Example 6
140.26 g of caprolactam, 24.72 g of aminocaproic acid and 1.41 g of tetraethylenepentamine are added into a polymerization reaction kettle, after nitrogen replacement, stirring and heating are carried out to 180 ℃ to enable reactants to be in a molten state of uniform mixing, normal pressure is maintained, the temperature is raised to 256 ℃, heating is turned off after polymerization is carried out for 3 hours, the temperature is reduced to 200 ℃ at a constant speed of 4.0 ℃/min in a nitrogen atmosphere, the stirring state is maintained, then unreacted monomers are removed under 2000Pa pressure, the nylon melt is discharged to desalted water, crystallization molding and pelletization are carried out, and the high-fluidity nylon polymer slice P6 is obtained.
The relative viscosity of the high-fluidity nylon polymer P6 was measured to be 2.04.
The nylon polymers P1 to P6 obtained in examples 1 to 6 were each tested for melting point and crystallization temperature, and the results are shown in Table 1.
TABLE 1
| Relative viscosity | Melting point (. Degree. C.) | Crystallization temperature (. Degree. C.) | |
| Example 1 | 2.01 | 218.0 | 176.4 |
| Example 2 | 1.86 | 218.3 | 175.7 |
| Example 3 | 1.68 | 213.7 | 171.3 |
| Example 4 | 2.49 | 217.5 | 178.2 |
| Example 5 | 2.20 | 209.4 | 185.6 |
| Example 6 | 2.04 | 217.2 | 177.2 |
Comparative example 1
141.28 g of caprolactam, 19.72 g of aminocaproic acid and 0.15 g of lysine are added into a polymerization reaction kettle, nitrogen is introduced for replacement, the mixture is stirred and heated to 170 ℃ to enable reactants to be in a uniformly mixed molten state, normal pressure is maintained, the temperature is raised to 265 ℃, the heating is turned off after polymerization is carried out for 2 hours, the nylon melt is discharged to desalted water, and the nylon polymer chips P7 are obtained through crystallization molding and granulating.
The nylon polymer P7 was found to have a relative viscosity of 2.95.
The amount of lysine added was smaller in comparative example 1 than in example 3, and the pellets were directly discharged without passing through a cooling process. When the lysine content is small, the viscosity of the obtained nylon is still large (the relative viscosity is more than 2.50), so that the nylon can be successfully cooled, crystallized and formed without cooling.
Comparative example 2
A nylon polymer was produced in the same manner as in example 3, except that the temperature reduction was not performed after the polymerization was completed, and the nylon melt was directly discharged.
Because the nylon melt has high fluidity and is in a low-viscosity liquid state, the nylon melt cannot be effectively cooled, crystallized and molded in the process of rapidly flowing out of the reaction kettle into desalted water, and the subsequent relative viscosity test and characterization are difficult.
From the experimental cases of examples 1 to 6 and comparative examples 1 to 2 described above, it is understood that the post-polymerization cooling process used in examples 1 to 6 plays an important role in preparing high-fluidity nylon and subsequent molding and pelletization.
The foregoing description of embodiments of the invention has been presented for purposes of illustration and description, and is not intended to be exhaustive or limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the various embodiments described.
Claims (10)
1. The cooling and discharging process of the high-fluidity nylon is characterized by comprising the following steps of: cooling the nylon melt prepared by the polymerization reaction, then discharging, forming, drying and granulating to obtain a high-fluidity nylon slice;
the cooling conditions include: in the nitrogen atmosphere and stirring state, the temperature is reduced to 185-220 ℃ at a constant speed of 0.25-8.0 ℃/min within 10-40 minutes.
2. The cooling and discharging process of high-fluidity nylon according to claim 1, wherein the cooling conditions include: in the nitrogen atmosphere and stirring state, the temperature is reduced to 190-210 ℃ at a constant speed of 0.75-5.0 ℃/min within 14-40 minutes.
3. The temperature-reduced discharge process of high-fluidity nylon of claim 1, wherein the polymerization reaction comprises: in the presence of a ring-opening polymerization initiator, a lactam monomer and a branching agent are subjected to ring-opening polymerization reaction to prepare a nylon melt.
4. The process for cooling and discharging high-fluidity nylon according to claim 3, wherein the ring-opening polymerization initiator is at least one selected from the group consisting of water, aminocaproic acid, sodium hydroxide, potassium hydroxide and alkali metals, preferably water, aminocaproic acid.
5. A temperature-reduced discharge process for high flow nylon according to claim 3, wherein the lactam monomer is at least one selected from the group consisting of butyrolactam, caprolactam, heptanolactam, octalactam and dodecalactam, preferably caprolactam.
6. The process for cooling and discharging high-fluidity nylon according to claim 3, wherein the branching agent is at least one selected from the group consisting of a polybasic acid, a polybasic amine, a polybasic alcohol, an amino acid and an acid anhydride, each of which has 3 or more functional groups, and each of the functional groups is an amino group, a carboxyl group or a hydroxyl group;
preferably, the branching agent is selected from at least one of polyamines, amino acids or anhydrides containing 3 to 6 functional groups;
more preferably, the branching agent is selected from at least one of lysine, naphthalene-1, 4,5, 8-tetracarboxylic dianhydride, diethylenetriamine, triethylenetetramine and tetraethylenepentamine.
7. The cooling take-off process for high fluidity nylon according to any one of claims 3 to 6, wherein the mass ratio of the lactam monomer, the ring-opening polymerization initiator and the branching agent is 100:2.0-20.0:0.05-10.0, preferably 100:10.0-18.0:0.1-5.0.
8. The process for temperature-reduced discharge of high-fluidity nylon according to claim 3, wherein the conditions for the ring-opening polymerization reaction include: the reaction temperature is 200-280 ℃, the reaction pressure is 0-0.3MPa, and the reaction time is 1-15 hours;
preferably, the conditions of the ring-opening polymerization reaction include: the reaction temperature is 230-265 ℃, the reaction pressure is 0.05-0.1MPa, and the reaction time is 1.5-10 hours.
9. The temperature-reducing discharge process of high-fluidity nylon according to claim 1, wherein the discharge molding comprises: and decompressing the cooled nylon melt to remove unreacted monomers, and then discharging the unreacted monomers into desalted water for crystallization and molding.
10. The temperature-reduced discharge process of high-flow nylon of claim 1, wherein drying and pelletizing comprises: and drying and granulating the formed nylon to obtain the high-fluidity nylon slice.
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